PURPOSE: Prediction of difficulty in orotracheal intubation (DI) in patients undergoing laryngeal microsurgery should help reduce the morbidity-mortality associated with this clinical situation. To establish a simple score to predict this difficulty, we studied 11 variables and their association with DI in these patients. METHODS: The study included 181 patients. The variables evaluated were: Mallampati grade, thyromental distance, mouth opening, temporomandibular joint movement, tooth morphology, maxillary deficiency, head and neck movement, receding mandible, body mass index, and clinical symptoms of laryngeal and supraglottic disease. To establish the score, regression coefficients of the statistically significant variables were used on adjusted logistic regression analysis. RESULTS: DI was present in 50 patients (28%) and orotracheal intubation was impossible in four (2%). Except for obesity, all the variables evaluated were predictive of DI. A simple predictive test was established based on logistic regression analysis including all the variables except temporomandibular joint movement. To determine the optimum cut-off for the new test, a receiver operating characteristic curve analysis was applied. A score > or = 5 in the proposed test provided a sensitivity of 94% and a specificity of 76%. CONCLUSION: The index we describe is aimed at predicting DI in a very specific population with a high risk of this complication. This index uses a series of variables which may be measured easily during the preoperative period and provides an excellent predictive capacity with a high sensitivity and specificity when the index is > or = 5.